This invention relates to crystal beads having controlled fragrance releasing properties. More particularly this invention relates to crystal beads which contain an odor releasing material coated on the surface of a beaded or prilled water-soluble material such as urea. The products are useful as odorants or deodorants. They exhibit a slow continuous release of fragrance under anhydrous or dry conditions without the carrier being dissolved and exhibit a rapid release of fragrance when wetted.
For instance, if placed in the air intake of an air conditioner, the odor may be steadily released for two weeks or more under forced draft conditions. If wetted and the carrier is dissolved, the perfume released will be more intense and last several hours. The product of the present invention is not hygroscopic despite the high water solubility of the carrier used. Thus, exposure of the product to a steam atmosphere in a hood does not result in any appreciable softening, dissolution or apparent absorption of water, although these phenomena would occur with the carrier itself in the absence of the coating which is an essential feature of this invention.
Retarded vaporization compositions have been disclosed in the prior art which enable highly volatile fragrances and other odoriferous materials to be maintained in a relatively non-volatile state for extended periods of time and to be released when the compositon is contacted with water. See, for instance, U.S. Pat. No. 3,767,787. Although these compositions are disclosed to have utility in a wide variety of usages including a vaporizer, a household deodorant, an insecticide and a dog repellant, they are not very efficient because the compositions are in the form of homogeneous, gelatine-like, non-aqueous colloidal systems from which the desired product is made by extrusion and curing. As the odoriferous material is uniformly distributed throughout, there is said to be no release of odor under ambient conditions, but only on contact with moisture when the composition changes to an aqueous system from which the volatile perfume is released.
U.S. Pat. No. 3,772,215 is another illustration of the state of the prior art. It also discloses compositions designed to provide a rapid release of fragrance upon contact with water. The compositions are water-soluble hydroxy-acrylate or methacrylate polymers in which fragrant materials are entrapped. In making this product, however, a relatively expensive water soluble polymer must be used which must be dissolved in a solvent such as methanol, the desired fragrance is added to the polymer solution, and the solution is cast as a thin film and ground to a powder after drying. This is a lengthy operation requiring several pieces of process equipment. By contrast, the product of the present invention can be made in a single vessel where the beads, as urea beads, and other components are heated to the proper temperature, mixed to insure proper dispersion and discharged in particulate form. The carrier is relatively inexpensive and available in a form that is ready for use.
It is an object of the invention to provide compositions which are economical to prepare and use and which enable fragrances to be slowly and continuously released over extended periods of time but which are also capable of rapidly releasing fragrances under controlled conditions.
It is another object of this invention to provide controlled fragrance releasing compositions which have a highly visible particulate appearance such that they indicate visually when the original charge is spent and replacement or replenishment is required.
These and other objects, as well as the scope, nature and utilization of the present invention will be apparent to those skilled in the art from the following description of the invention and from the appended claims.